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Case of the Month: August 2023

posted: August 15, 2023

A 57 years old female presented with a palpable concern in the right breast. A 26 mm solid irregular mass was seen on diagnostic mammogram and ultrasound, assessed as Breast Imaging Reporting and Data System (BI-RADS) 5. The patient underwent ultrasound-guided core biopsy, with pathology concerning for neoplastic process. The patient subsequently underwent partial mastectomy. The radiologic and histologic findings coupled with ancillary studies are shown below:

Mammogram (MG) And Histology
figure 1
  • CD68
  • AE1/AE3
  • S100
  • OCT2

Additional ancillary studies results: Cyclin D1 was positive, but CD1a and BRAF were negative. Flow cytometry and Kappa/Lambda ISH failed to reveal lymphoma. AFB and GMS stains were negative for microorganisms.

figure 2
View Final Diagnosis
Final Diagnosis: Rosai-Dorfman Disease Of The Breast
The histopathologic examination revealed sheets of large histiocytes displaying emperipolesis (inset) with associated fibrosis and dense lymphoplasmacytic infiltrate. Histiocytes co-expressed CD68, S100, OCT2, and Cyclin D1, and were negative for AE1/AE3, CD1a, and BRAF V600E. Flow cytometry and Kappa/Lambda in situ hybridization failed to reveal lymphoma. No microorganisms were identified on AFB and GMS stains. Complete excision was performed without recurrence or progression to systemic disease during follow-up 151 months.
Rosai-Dorfman Disease (RDD) is an uncommon histiocytosis typically presenting with lymphadenopathy and less commonly with extranodal involvement. Breast involvement of RDD is rare, which may mimic neoplastic and non-neoplastic processes clinicoradiologically and further complicate pathologic diagnosis. RDD should be included in the differential of any mass-forming breast lesion with histiocytosis. The main histologic differential diagnosis includes inflammatory lesion, histiocytic neoplasm, hematolymphoid neoplasm, and histiocytoid breast carcinoma. Histopathology coupled with ancillary studies and clinical data is essential for accurate diagnosis and optimal clinical management. Patients with RDD of the breast have an excellent prognosis after complete excision.
  1. Green I, Dorfman RF, Rosai J. Breast involvement by extranodal Rosai-Dorfman disease:  report of seven cases. Am J. Surg Pathol 1997; 21: 664-668. (DOI: 10.1097/00000478-199706000-00006)
  2. Tenny SO, McGinness M, Zhang D, et al. Rosai-Dorfman disease presenting as a breast mass and enlarged axillary lymph node mimicking malignancy: a case report and review of the literature. Breast J 2011; 17: 516-520. (DOI: 10.1111/j.1524-4741.2011.01131.x)
  3. Hoffmann JC, Lin CY, Bhattacharyya S, et al. Rosai-Dorfman Disease of the Breast With Variable IgG4+ Plasma Cells: A Diagnostic Mimicker of Other Malignant and Reactive Entities. Am J Surg Pathol 2019; 43: 1653-1660. (DOI: 10.1097/PAS.0000000000001347)
  4. Garces S, Yin CC, Patel KP, et al. Focal Rosai-Dorfman disease coexisting with lymphoma in the same anatomic site: a localized histiocytic proliferation associated with MAPK/ERK pathway activation. Mod Pathol 2019; 32: 16-26. (DOI: 10.1038/s41379-018-0152-1)
  5. Shetty S, Sharma N, Booth CN, et al. Mammary Extranodal Rosai-Dorfman Disease With and Without Associated Axillary Lymphadenopathy: Insights for Practitioners of Breast Pathology. Int J Surg Pathol 2020; 28: 541-548. (DOI: 10.1177/1066896920901770)

This case is contributed by Dr. Qun Wang, MD, PhD. Department of Pathology and Laboratory Medicine, Emory University.